Obama: Justice will be done on Libya attacks

9/12/12 10:02 PM EDT

President Obama vowed retribution Wednesday against the perpetrators of attacks on a U.S. diplomatic post in Libya.

"I want to assure you that we will bring their killers to justice," he said, at a campaign rally in Las Vegas.

"We will not be deterred," Obama said. "We will keep going. Because the world needs us — we are the one indispensable power in the world."

Four American State Department employees — including a U.S. ambassador — were killed Tuesday after protesters in Libya stormed an American consulate in Benghazi. Republicans and Democrats have spent the day trading partisan barbs over responsibility for the attacks, with the GOP sensing an opening to criticize Obama on his handling of foreign policy.

For the most part, Obama stayed out of the partisan back and forth on foreign policy in his speech — though he did tell CBS that GOP nominee Mitt Romney tended to shoot first and aim later.

Obama went on to praise the bravery and dedication of U.S. diplomatic personnel serving abroad.

"It's a reminder that the freedoms we enjoy — sometimes even the freedoms we take for granted — they're only sustained because there are people like those who were killed, who were willing to stand up for those freedoms," he said.